/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: FuncExtFunctionAvailable.java 468655 2006-10-28 07:12:06Z minchau $
 */
package org.apache.xpath.functions;

import org.apache.xalan.templates.Constants;
import org.apache.xpath.ExtensionsProvider;
import org.apache.xpath.XPathContext;
import org.apache.xpath.compiler.FunctionTable;
import org.apache.xpath.objects.XBoolean;
import org.apache.xpath.objects.XObject;

Execute the ExtFunctionAvailable() function.
@xsl.usage
advanced/**
 * Execute the ExtFunctionAvailable() function.
 * @xsl.usage advanced
 */
public class FuncExtFunctionAvailable extends FunctionOneArg
{
    static final long serialVersionUID = 5118814314918592241L;
    
    transient private FunctionTable m_functionTable = null;

  
Execute the function.  The function must return
a valid object.
Params:
xctxt – The current execution context.
Throws:
TransformerException – 
Returns:
A valid XObject./**
   * Execute the function.  The function must return
   * a valid object.
   * @param xctxt The current execution context.
   * @return A valid XObject.
   *
   * @throws javax.xml.transform.TransformerException
   */
  public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
  {

    String prefix;
    String namespace;
    String methName;

    String fullName = m_arg0.execute(xctxt).str();
    int indexOfNSSep = fullName.indexOf(':');

    if (indexOfNSSep < 0)
    {
      prefix = "";
      namespace = Constants.S_XSLNAMESPACEURL;
      methName = fullName;
    }
    else
    {
      prefix = fullName.substring(0, indexOfNSSep);
      namespace = xctxt.getNamespaceContext().getNamespaceForPrefix(prefix);
      if (null == namespace)
        return XBoolean.S_FALSE;
        methName = fullName.substring(indexOfNSSep + 1);
    }

    if (namespace.equals(Constants.S_XSLNAMESPACEURL))
    {
      try
      {
        if (null == m_functionTable) m_functionTable = new FunctionTable();
        return m_functionTable.functionAvailable(methName) ? XBoolean.S_TRUE : XBoolean.S_FALSE;
      }
      catch (Exception e)
      {
        return XBoolean.S_FALSE;
      }
    }
    else
    {
      //dml
      ExtensionsProvider extProvider = (ExtensionsProvider)xctxt.getOwnerObject();
      return extProvider.functionAvailable(namespace, methName)
             ? XBoolean.S_TRUE : XBoolean.S_FALSE;
    }
  }
  
  
The function table is an instance field. In order to access this instance 
field during evaluation, this method is called at compilation time to
insert function table information for later usage. It should only be used
during compiling of XPath expressions.
Params:
aTable – an instance of the function table/**
   * The function table is an instance field. In order to access this instance 
   * field during evaluation, this method is called at compilation time to
   * insert function table information for later usage. It should only be used
   * during compiling of XPath expressions.
   * @param aTable an instance of the function table
   */
  public void setFunctionTable(FunctionTable aTable){
          m_functionTable = aTable;
  }
}